mirror of https://github.com/rust-lang/rust
87 lines
2.7 KiB
Rust
87 lines
2.7 KiB
Rust
//@ test-mir-pass: EarlyOtherwiseBranch
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//@ compile-flags: -Zmir-enable-passes=+UnreachableEnumBranching
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enum Option2<T> {
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Some(T),
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None,
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Other,
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}
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// We can't optimize it because y may be an invalid value.
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// EMIT_MIR early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
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fn opt1(x: Option<u32>, y: Option<u32>) -> u32 {
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// CHECK-LABEL: fn opt1(
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// CHECK: bb0: {
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// CHECK: [[LOCAL1:_.*]] = discriminant({{.*}});
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// CHECK-NOT: Ne
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// CHECK-NOT: discriminant
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// CHECK: switchInt(move [[LOCAL1]]) -> [
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// CHECK-NEXT: }
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match (x, y) {
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(Some(a), Some(b)) => 0,
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_ => 1,
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}
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}
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// FIXME: `switchInt` will have three targets after `UnreachableEnumBranching`,
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// otherwise is unreachable. We can consume the UB fact to transform back to if else pattern.
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// EMIT_MIR early_otherwise_branch.opt2.EarlyOtherwiseBranch.diff
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fn opt2(x: Option<u32>, y: Option<u32>) -> u32 {
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// CHECK-LABEL: fn opt2(
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// CHECK: bb0: {
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// CHECK: [[LOCAL1:_.*]] = discriminant({{.*}});
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// CHECK-NOT: Ne
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// CHECK-NOT: discriminant
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// CHECK: switchInt(move [[LOCAL1]]) -> [
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// CHECK-NEXT: }
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match (x, y) {
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(Some(a), Some(b)) => 0,
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(None, None) => 2,
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_ => 1,
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}
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}
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// optimize despite different types
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// EMIT_MIR early_otherwise_branch.opt3.EarlyOtherwiseBranch.diff
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fn opt3(x: Option2<u32>, y: Option2<bool>) -> u32 {
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// CHECK-LABEL: fn opt3(
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// CHECK: let mut [[CMP_LOCAL:_.*]]: bool;
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// CHECK: bb0: {
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// CHECK: [[LOCAL1:_.*]] = discriminant({{.*}});
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// CHECK: [[LOCAL2:_.*]] = discriminant({{.*}});
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// CHECK: [[CMP_LOCAL]] = Ne([[LOCAL1]], move [[LOCAL2]]);
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// CHECK: switchInt(move [[CMP_LOCAL]]) -> [
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// CHECK-NEXT: }
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match (x, y) {
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(Option2::Some(a), Option2::Some(b)) => 0,
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(Option2::None, Option2::None) => 2,
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(Option2::Other, Option2::Other) => 3,
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_ => 1,
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}
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}
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// EMIT_MIR early_otherwise_branch.opt4.EarlyOtherwiseBranch.diff
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fn opt4(x: Option2<u32>, y: Option2<u32>) -> u32 {
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// CHECK-LABEL: fn opt4(
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// CHECK: let mut [[CMP_LOCAL:_.*]]: bool;
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// CHECK: bb0: {
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// CHECK: [[LOCAL1:_.*]] = discriminant({{.*}});
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// CHECK: [[LOCAL2:_.*]] = discriminant({{.*}});
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// CHECK: [[CMP_LOCAL]] = Ne([[LOCAL1]], move [[LOCAL2]]);
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// CHECK: switchInt(move [[CMP_LOCAL]]) -> [
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// CHECK-NEXT: }
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match (x, y) {
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(Option2::Some(a), Option2::Some(b)) => 0,
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(Option2::None, Option2::None) => 2,
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(Option2::Other, Option2::Other) => 3,
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_ => 1,
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}
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}
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fn main() {
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opt1(None, Some(0));
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opt2(None, Some(0));
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opt3(Option2::None, Option2::Some(false));
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opt4(Option2::None, Option2::Some(0));
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}
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